Sapanisertib plus Fulvestrant in Postmenopausal Women with Estrogen Receptor-Positive/HER2-Negative Advanced Breast Cancer after Progression on Aromatase Inhibitor

MLIP and Its Potential Influence on Key Oncogenic Pathways

Muscle-enriched A-type lamin-interacting protein (MLIP) is an emerging protein involved in cellular homeostasis and stress adaptation. Eukaryotic cells regulate various cellular processes, including metabolism, DNA repair, and cell cycle progression, to maintain cellular homeostasis. Disruptions in this homeostasis can lead to diseases such as cancer, characterized by uncontrolled cell growth and division. This review aims to explore for the first time the unique role MLIP may play in cancer development and progression, given its interactions with the PI3K/Akt/mTOR pathway, p53, MAPK9, and FOXO transcription factors, all critical regulators of cellular homeostasis and tumor suppression. We discuss the current understanding of MLIP's involvement in pro-survival pathways and its potential implications in cancer cells' metabolic remodeling and dysregulated homeostasis. Additionally, we examine the potential of MLIP as a novel therapeutic target for cancer treatment. This review aims to shed light on MLIP's potential impact on cancer biology and contribute to developing innovative therapeutic strategies.

Palbociclib sensitizes ER-positive breast cancer cells to fulvestrant by promoting the ubiquitin-mediated degradation of ER-α via SNHG17/Hippo-YAP axis

PURPOSE

Endocrine therapy is the anti-tumor therapy for human breast cancer but endocrine resistance was a major burden. It has been reported that Palbociclib and fulvestrant can be used in combination for the treatment of patients who are experiencing endocrine resistance. However, the underlying mechanism is unclear. In this study, we aimed to investigate the mechanism by which Palbocicilib affected ER-positive breast cancer, combined with fulvestrant.

METHODS

We first detected the effect of palbociclib on cell survival, growth and cycle distribution separately by MTT, colony formation and flow cytometry. Then SNHG17 was screened as palbociclib-targeted LncRNA by LncRNA-seq, and the SNHG17-targeted mRNAs were selected by mRNA-seq for further determination. Subsequently, the underlying mechanism by which palbociclib promoted the cytotoxicity of fulvestrant was confirmed by qRT-PCR, western blot, and immunoprecipitation. Eventually, the xenograft model and immunohistochemistry experiments were used to validate the sensitization effect of palbociclib on fulvestrant and its mechanism in vivo.

RESULTS

Palbociclib significantly enhanced the cytotoxicity of fulvestrant in fulvestrant-resistant breast cancer cell lines. Interestingly, this might be related to the lncRNA SNHG17 and the Hippo signaling pathway. And our subsequent western blotting experiments confirmed that overexpressing SNHG17 induced the down-regulation of LATS1 and up-regulated YAP expression. Furthermore, we found that the increased sensitivity of breast cancer cells was closely associated with the LATS1-mediated degradation of ER-α. The following animal experiments also indicated that overexpressing SNHG17 obviously impaired the anti-cancer effect of co-treatment of palbociclib and fulvestrant accompanied by decreased LATS1 and increased ER-α levels.

CONCLUSION

Palbociclib might sensitize the cytotoxicity of fulvestrant in ER-positive breast cancer cells by down-regulating SNHG17 expression, and then resulted in the LATS1-inactivated oncogene YAP and LATS1-mediated degradation of ER-α.

A network meta-analysis of efficacy and safety for first-line and second/further-line therapies in postmenopausal women with hormone receptor-positive, HER2-negative, advanced breast cancer

BACKGROUND

Hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR + /HER2 -) advanced breast cancer is a prevalent subtype among postmenopausal women. Despite the growing number of randomized clinical trials (RCTs) exploring this topic, the efficacy and safety of first-line and second/further-line treatments remain uncertain. Accordingly, our aim was to conduct a comprehensive evaluation of the efficacy and safety of these therapies through network meta-analysis.

METHODS

RCTs were identified by searching Pubmed, Embase, and major cancer conferences. The efficacy of interventions was assessed using the hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS), while safety was indicated by the incidence of any grade adverse events (AEs), grade 3-5 AEs, AEs leading to treatment discontinuation, and AEs leading to death. Both time-variant HRs fractional polynomial models and time-invariant HRs Cox-proportional hazards models were considered for handling time-to-event data. Safety indicators were analyzed using Bayesian network meta-analysis. Additionally, subgroup analyses were conducted based on patient characteristics.

RESULTS

A total of 41 RCTs (first-line 17, second/further-lines 27) were included in the analysis. For first-line treatment, the addition of Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors to endocrine therapy significantly improved therapeutic efficacy in terms of both PFS and OS, demonstrating the best performance across all mechanisms. Specifically, the combination of Abemaciclib and Letrozole demonstrated the most favorable performance in terms of PFS, while Ribociclib plus Fulvestrant yielded the best outcomes in OS. Incorporating the immune checkpoint inhibitor Avelumab into the regimen with CDK4/6 inhibitors and selective estrogen receptor degraders significantly enhanced both PFS and OS in second-line or later treatments. Regarding safety, endocrine monotherapy performed well. Regarding safety, endocrine monotherapy performed well. There is mounting evidence suggesting that most CDK4/6 inhibitors may demonstrate poorer performance with respect to hematologic AEs. However, additional evidence is required to further substantiate these findings.

CONCLUSIONS

CDK4/6 inhibitors, combined with endocrine therapy, are pivotal in first-line treatment due to their superior efficacy and manageable AEs. For second/further-line treatment, adding immune checkpoint inhibitors to CDK4/6 inhibitors plus endocrine therapy may produce promising results. However, to reduce the results' uncertainty, further trials comparing these novel treatments are warranted.

TRIAL REGISTRATION

Registration number: PROSPERO (CRD42022377431).

Inhibitors of phosphoinositide 3-kinase (PI3K) and phosphoinositide 3-kinase-related protein kinase family (PIKK)

Phosphoinositide 3-kinases (PI3K) and phosphoinositide 3-kinase-related protein kinases (PIKK) are two structurally related families of kinases that play vital roles in cell growth and DNA damage repair. Dysfunction of PIKK members and aberrant stimulation of the PI3K/AKT/mTOR signalling pathway are linked to a plethora of diseases including cancer. In recent decades, numerous inhibitors related to the PI3K/AKT/mTOR signalling have made great strides in cancer treatment, like copanlisib and sirolimus. Notably, most of the PIKK inhibitors (such as VX-970 and M3814) related to DNA damage response have also shown good efficacy in clinical trials. However, these drugs still require a suitable combination therapy to overcome drug resistance or improve antitumor activity. Based on the aforementioned facts, we summarised the efficacy of PIKK, PI3K, and AKT inhibitors in the therapy of human malignancies and the resistance mechanisms of targeted therapy, in order to provide deeper insights into cancer treatment.

Addition of PI3K/AKT/mTOR inhibitors to fulvestrant for advanced HR+/HER2- breast cancer: a systematic review and meta-analysis

Purpose: To analyze whether adding PI3K/AKT/mTOR inhibitors to fulvestrant could restore endocrine therapy sensitivity for the treatment of postmenopausal patients with HR+, HER2- breast cancer. Methods: This meta-analysis was performed using RevMan 5.4 analysis software. Results: Nine studies that included a total of 3199 patients were analyzed. Compared with fulvestrant alone, the addition of PI3K/AKT/mTOR inhibitors significantly prolonged progression-free survival, overall survival and objective response rate of patients in both the total and PI3K-pathway-activated population. The number of grade 3-5 adverse events was also significantly higher. Conclusion: The addition of PI3K/AKT/mTOR to fulvestrant resulted in potential benefits; however, there may be a higher risk, which needs to be carefully managed.

Place in Therapy of Cyclin-Dependent Kinase 4/6 Inhibitors in Breast Cancer: A Targeted Literature Review

Cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) are the preferred regimen for patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced or metastatic breast cancer. However, the optimal treatment sequencing for CDK4/6i with other available therapeutic options is unclear. We conducted a targeted literature review to identify the current evidence on CDK4/6i treatment patterns in patients with breast cancer. The search was initially conducted in October 2021 and subsequently updated in October 2022. Biomedical databases and gray literature were searched, and bibliographies of included reviews were screened for relevant studies. The search identified ten reviews published since 2021 and 87 clinical trials or observational studies published since 2015. The included reviews discussed CDK4/6i usage with or without endocrine therapy (ET) in first-line and second-line treatment for patients with HR+/HER2- advanced or metastatic breast cancer, followed by ET, chemotherapy, or targeted therapy with ET. Clinical studies reported similar treatment sequences consisting of ET, chemotherapy, or targeted therapy with ET prior to CDK4/6i with ET, followed by ET monotherapy, chemotherapy, targeted therapy with ET, or continued CDK4/6i with ET. Current evidence suggests CDK4/6i are effective for HR+/HER2- advanced or metastatic breast cancer in earlier lines of therapy. Efficacy of CDK4/6i as measured by progression-free survival and overall survival was similar within a line of therapy regardless of the type of prior therapy. Survival on different post-CDK4/6i treatments was also similar within the same line of therapy. Additional research is needed to investigate the optimal place in therapy of CDK4/6i and the sequencing of treatments following progression on CDK4/6i.

Metabolic Reprogramming Induces Macrophage Polarization in the Tumor Microenvironment

Macrophages are one of the most important cells in the innate immune system, they are converted into two distinct subtypes with completely different molecular phenotypes and functional features under different stimuli of the microenvironment: M1 macrophages induced by IFN-γ/lipopolysaccharides(LPS) and M2 macrophages induced by IL-4/IL-10/IL-13. Tumor-associated macrophages (TAMs) differentiate from macrophages through various factors in the tumor microenvironment (TME). TAMs have the phenotype and function of M2 macrophages and are capable of secreting multiple cytokines to promote tumor progression. Both tumor cells and macrophages can meet the energy needs for rapid cell growth and proliferation through metabolic reprogramming, so a comprehensive understanding of pro-tumor and antitumor metabolic switches in TAM is essential to understanding immune escape mechanisms. This paper focuses on the functions of relevant signaling pathways and cytokines during macrophage polarization and metabolic reprogramming, and briefly discusses the effects of different microenvironments and macrophage pathogenicity, in addition to describing the research progress of inhibitory drugs for certain metabolic and polarized signaling pathways.

Expert consensus on the clinical application of PI3K/AKT/mTOR inhibitors in the treatment of advanced breast cancer

Phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB or AKT)/mammalian target of rapamycin (mTOR) signaling pathway (PAM pathway) plays an important role in the development of breast cancer and are closely associated with the resistance to endocrine therapy in advanced breast cancer. Therefore, anticancer treatment targeting key molecules in this signaling pathway has become a research hotspot in recent years. Randomized clinical trials have demonstrated that PI3K/AKT/mTOR inhibitors bring significant clinical benefit to patients with advanced breast cancer, especially to those with hormone receptor (HR)-positive, human epidermal growth factor receptor (HER) 2-negative advanced breast cancer. Alpelisib, a PI3K inhibitor, and everolimus, an mTOR inhibitor, have been approved by FDA. Based on their high efficacy and relatively good safety profile, an expanded indication of everolimus in breast cancer has been approved by National Medical Products Administration (NMPA). Alpelisib is expected to be approved in China in the near future. The members of the consensus expert panel reached this consensus to comprehensively define the role of PI3K/AKT/mTOR signaling pathway in breast cancer, efficacy and clinical applications of PI3K/AKT/mTOR inhibitors, management of adverse reactions, and PIK3CA mutation detection, to promote the understanding of PI3K/AKT/mTOR inhibitors for Chinese oncologists, improve clinical decision-making, and prolong the survival of target patient population.